Liquid propulsion systems have effective role in implementation of space and military mission due to high performance and specific impulse. Liquid propellants are divided into two categories: hypergolic and non-hypergolic propellants. Non-hypergolic propellants need an igniter system to provide the initial energy for propellant ignition compared with hypergolic propellants. Since failure in ignition system result in failure of engine firing, this system is one of the most important parts of non-hypergolic liquid propellant rocket engines. Therefore, the igniter system must have important parameters such as restartability, high reliability, low production cost, appropriate weight, proven knowledge, and lack of complexity. Spark igniter, hypergolic igniter, laser igniter, thermal igniter, resonant igniter, catalytic igniter, and pyrotechnic igniter are used for initial ignition of non-hypergolic liquid propellants. In this paper, various igniter systems for non-hypergolic liquid propellants are introduced and their advantages and disadvantages will be discussed.